1. Field of the Invention
The present invention relates to an object, a method, or a manufacturing method. In addition, the present invention relates to a process, a machine, manufacture, or a composition of matter. In particular, one embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a memory device, a driving method thereof, or a manufacturing method thereof.
Note that in this specification, a semiconductor device means a circuit including a semiconductor element (e.g., a transistor or a diode) and a device including the circuit. The semiconductor device also means any device that can function by utilizing semiconductor characteristics. For example, an integrated circuit, and a chip including an integrated circuit are semiconductor devices. Moreover, a memory device, a display device, a light-emitting device, a lighting device, an electronic device, and the like include a semiconductor device in some cases.
2. Description of the Related Art
A bootstrap circuit that generates a voltage higher than a power supply voltage using capacitive coupling is known (Patent Document 1, for example).
A transistor whose channel formation region includes an oxide semiconductor (OS) such as an In—Ga—Zn oxide (In—Ga—Zn—O) (hereinafter such a transistor is referred to as an OS transistor) is known. It is known that an OS transistor has extremely low off-state current because an oxide semiconductor has a wider bandgap than silicon. Patent Document 2, for example, discloses a semiconductor device using an OS transistor for a memory cell so that data can be held even after power supply is stopped.